Two-cycle engine



INVENTOR M M... Z 2? C SCHAER TWO-CYCLE ENGINE Flled Sept 9 1925 May 29, 1928.

Patented May 29, 1928.

UNITED STATES PATENT OFFICE.

CHARLES SCHAER, OF LANGENTHAL, SWITZERLAND, ASSIGN OR TO BUSCH-SULZER BROS.-DIESEL ENGINE CO., 01 ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

'rwo-cYcLi: ENGINE.

Application filed September 9, 1925, Serial No. 55,233, and in Switzerland October 27, 1924.

The invention relates to means and methods for scavenging and supercharging two cycle engines and its object is to provide for the more economical use of air for these purposes. To this end the invention includes the principles of organization and operation illustrated in the. accompanying drawing, which is an axial section through an engine cylinder and its air receiver, more or less diagrammatic. In the illustrated engine, the cylinder of usual design is provided with upper and lower air admission ports, or tiers of ports, marked 1 and 2 respectively. The upper port is uncovered by the descending piston before the exhaust port 3, or tier of I ports, is opened and on the pistons upstroke remains uncovered for an interval after the exhaust port is closed. The lower air ad'- mission port 2, is uncovered only while the exhaust port is open.

Scavenging air at moderate pressure is supplied to the scavenger port 2 from an air receiver 4, which latter may be common to a number of engine cylinders, and is connected by pipe 5 with any suitable air compressing apparatus. Higher pressure air is admitted to the port 1, through the space or passage 6, from the pipe connection 7 under the control of a mechanically operated valve 8, which latter is opened by a cam and cam lever 8, as indicated, driven by or in phase with the engine crank shaft. Low pressure air from the receiver 4 may also enter passage 6 through the automatic non-return valve 9 and thence pass to the cylinder through the upper port 1. This valve 9 may be of any suitable design, being herein illustrated as comprised of a series of annular inlets closed by thin steel annuli valve members marked 10, and as will be understood. Fuel is admitted to the cylinder by an injector or fuel valve 11 at or about compression dead center, or otherwise, as will be understood.

In the operation of the engine, when the descending piston uncovers the upper port 1 and begins to open the exhaust port, low pressure air may immediately begin to flow from thereceiver 4 through valve 9 and port 1 into the cylinder, and as the piston uncovers the lower port 2, further scavenging air may then enter through the latter port, pro ducing scavenging and using therefor only low pressure air. On the ascent of the piston to the point where it closes the exhaust port, this flow of low pressure air ceases, because of the counter pressure in the cylinder, whereupon the inlet valve 8 is opened by the cam and high pressure air is admitted to the cylinder through the space 6 and the upper port 1, thus supercharging air to the cylinder. It will be seen that the valve 9 en ables some of the low pressure air to serve for charging or supercharging the cylinder; it also prevents high pressure air and combustion products from entering the low pressure receiver.

The engine is preferably provided with a throttle 12 in its exhaust outlet by'means of which the flow of scavenging air into and through the cylinder can be closely regulated. Such valve can be manually set as by the lever 13, or such lever can be connected to the cam shaft or the cam lever 8 for operation in timed relation to the supercharging valve 8-, i. e. by means of linkage which will close the exhaust throttle When-high pressure air' is admitted. By this means the exhaust outlet can be closed even before the piston has covered the exhaust port 3 and thus ingrease the supercharging effect as will be evient.

The following is claimed:

1. In a two cycle injection-type engine, the combination with upper and lower air admission ports, one of which is uncovered by the piston before, and the other after the exhaust port is opened, a receiver for supplying low pressure air to both said ports and means for supplying high pressure air to the upper port.

2. In a two cycle engine, the combination of air admission ports successively uncovered by the piston, a receiver to supply air to both ports and means timed to operate in phase with the engine-to supply high pressure air to one of said ports.

3. In a two cycle engine, the combination with air admission ports successively uncovered by the piston, a source of high pressure air connected to the first uncovered ort, a. source of lower pressure air'connecte to the other and means for supplying low pressure air from the latter source to both ports.

4. In a two cycle engine, the combination 6f air admission ports successively uncovered by the piston, a high pressure air source to supply air to the first uncovered port, a low pressure source to supply air to the other and a valve between said ports through whi h said low pressure air reaches the first uncovered port.

5. In a two-cycle engine the combination of upper and lower air admission ports, one of which is uncovered by the piston before and the other after the exhaust port is opened, a receiver for supplying low pressure air to both said ports, means for supplying high pressure air to the upper port and means for variably restricting the exhaust port of the engine for the purpose described.

In testimony whereof, I have signed this specification.

CHARLES SCHAER. 

